<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<title></title>
	</head>
	<body>
		<script src="" type="text/javascript" >
			//变量要符合规范
			var a = 123;
		var _name="zhangsan";
		//变量类型由赋值决定
		var b = "123";
		console.log(b);
		console.log(typeof b);
		b = 123;
		console.log(b);
		console.log(typeof b);
		
		c="hello"
		console.log(c)
		console.log(typeof c)
		
		console.log(d)
		</script>
	</body>
</html>
